// 字符串
/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
 var isIsomorphic = function(s, t) {
    let s1={};
    let t1={};
    for(let i=0;i<s.length;i++){
        const x=s[i];
        const y=t[i];
        if(s1[x]&&s1[x]!=y||t1[y]&&t1[y]!=x){
            return false;
        }
        s1[x]=y;
        t1[y]=x;
    }
    return true;
    };